1. Field of the Invention
The invention relates to a communicating apparatus which is connected to a plurality of channels such as ISDN and the like and, more particularly, to a communicating apparatus which transfers a call by using an unoccupied line upon set-up of a call and records a message by substituting when the call cannot be received because a transfer station is busy or the like.
2. Related Background Art
In association with the development of recent information communication, digitization of a telephone line is being progressed. The digital line is a line network called, for example, ISDN and is a line having features such that a plurality of channels can be logically accommodated and an information transfer speed is higher than that of a conventional analog public line and the like.
Owing to the recent Internet boom, the introduction of personal computers into general homes is progressing, a request for the simultaneous use of personal computer communication and a telephone and a request for improvement of a speed in the personal computer communication are increased, and the ISDN is rapidly being spread to general homes.
When the ISDN is introduced to the general homes, a form such that the telephone and the personal computer are connected to the line by using an apparatus called TA (terminal adapter) is a mainstream. In this case, a telephone for a general analog public line is connected as a telephone which is used.
In recent years, a digital telephone with an answer/record function which is directly connected to the ISDN network has also been put into practical use.
A set-up of transfer of an incoming call will now be described.
The xe2x80x9cset-up of transfer of an incoming callxe2x80x9d is the operation for transferring a received call to another partner side. As a type of transfer mentioned above, there are two kinds of transfers, a speech transfer and a message transfer.
The xe2x80x9cspeech transferxe2x80x9d is a transfer such that the received call is transferred as it is in a real-time manner and communication (conversation) is directly made between the transmission side and a transfer station. The xe2x80x9cmessage transferxe2x80x9d is a transfer such that the call is once accepted, a message of a sender is recorded, the call is disconnected, a call is newly transmitted to a transfer station, and the recorded message is sent to the transfer station.
To realize the speech transfer by the conventional analog line, it is necessary to use toll transfer services on the line network side.
The message transfer is a transfer which is performed in the answer/record telephone of the general analog line and since the line which can be used is a single line, there is a problem such that messages which can be transferred are limited to the stored messages.
On the other hand, since a plurality of channels can be accommodated in the ISDN, a terminal apparatus can execute the speech transfer such that the call is received by a first channel and the received call is transferred by an unoccupied second channel.
In the speech transfer by the ISDN, in case of the TA connection, the TA itself has a transfer function, and in case of the digital telephone connection, the telephone itself has such a function. Even in the ISDN, although the set-up of call transfer function has been prepared as a service with charge on the network side, if the TA or digital telephone having the transfer function is prepared, there is no need to join the services on the network side and it is economical.
When the set-up of call transfer at an ISDN terminal is used, there is a case where a phone number of a cellular phone is set as a transfer station. In recent years, since a cellular phones become cheap, they are explosively spread owing to their convenience and the frequency of designating a cellular phone as a transfer station is increasing more and more.
When a cellular phone is designated as a transfer station as mentioned above, since a wireless zone exists unlike the transfer to a general wired telephone, there is a case where the call cannot be received in dependence on a situation of a radio wave besides a situation such that the telephone is occupied. When the call cannot be received due to the situation of the radio wave or the like, that is, if the call cannot be received for a predetermined time, a message showing that the telephone is not available is generated ordinarily. At this time, since a sender listens to the message and recognizes a fact that a partner side cannot receive the call, there is a problem such that the sender cannot help hanging up the telephone and a message which the sender wants to give cannot reach the partner side.
In a communicating apparatus which accommodates a plurality of channels, it is an object of the invention to provide a communicating apparatus which can record a message of a sender even when a transfer station (partner side) is busy (a telephone line is occupied) or located at a place where a radio wave does not reach.